JP2003254512A - Gas burner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas burner superior in heat efficiency, and indicating a low NOx value in a state of the small air mixing ratio. <P>SOLUTION: The purpose is attained by forming a burner having a part 17 for mixing a part (primary gas) of fuel gas and air, a dividing plate 20 for blowing out the mixed fuel gas and air by being divided into a plurality, and a mechanism for blowing out a residual part (secondary gas) of the fuel gas to the combustion side of the dividing plate 20. This gas burner is desirably in a range of the primary gas:the secondary gas = (50:50 to 97:3) in the volume ratio on the distribution ratio of the primary gas and the secondary gas. A nozzle port of the secondary gas may be singular or plural. A blowout position can be changed. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is a gas burner that uses gas as a fuel and is excellent in low NOx properties.

[0002]

2. Description of the Related Art In a gas burner using gas as a fuel,
The generation of NOx during combustion has become an environmental problem.
The cause of generation is due to the oxidation of nitrogen gas in the air accompanying the combustion of the gas and the combustion of the nitrogen-containing component contained in the gas. The latter is due to the composition of the gas,
It will be dealt with by refining the gas. Since the former is based on the combustion method, many studies have been made on the combustion method.
As a method of suppressing NOx, it is preferable to lower the combustion temperature. However, if the amount of air is increased and the combustion temperature is lowered to obtain the same amount of heat, the amount of exhaust gas increases as the amount of air increases, so heat loss in exhaust gas increases and thermal efficiency decreases. Therefore, as a method of suppressing NOx without increasing the amount of air to obtain the same amount of heat, a method of making the temperature of the combustion part as uniform as possible is taken, and it is important not to create a part where the temperature locally rises. Become.

In the examination of the combustion method, as an example of the prior art, the burner of the pre-mixing method, which is called a low NOx burner at present, is shown in FIGS. 1a and 1b. Figure 1a is side view,
FIG. 1b is a front view. It will be explained together. The premixing method is a method of burning while mixing gas serving as fuel and air in a combustion chamber. In FIGS. 1a and 1b, the fuel gas and the air burn before being mixed together in the combustion chamber located on the right side of the gas nozzle 1 in FIG. The air flow adjusted by the flame holding plate 2 and the fuel gas ejected from the gas nozzle 1 are mixed and simultaneously burned. In the figure, the combustion cylinder 3,
The description of the gas header 4, the pilot burner 5, and the electrode rod 6 is omitted.

[0004] In this method, as measures against local temperature rise, measures such as self-exhaust gas circulation, split flame, thin film flame, etc. are taken. The divided flame is that the combustion air divided into several pieces in the flame holding plate 2 is mixed with the fuel gas ejected from the gas nozzle 1 to form divided flames. In the self-exhaust gas circulation, the flame holding plate surface becomes negative pressure in the part where combustion air is not ejected from the flame holding plate, and the surrounding low temperature exhaust gas goes around to the root of the flame, and the flame degree near the firing port decreases. Prevent local high temperature. In the thin film flame, a gas jet from the gas nozzle spreads at a constant angle to form a thin film bell-shaped flame. This increases the surface area of the flame,
Local heat is prevented by promoting heat dissipation from the flame. With the above technique, the conventional technique shown in FIG. 1 was examined using natural gas, and as a result, NOx of the conventional technique 1 shown in FIG.
Corresponds to the value. NO when the air ratio is 1.1 to 1.3
The x value is about 45 to 57 ppm.

Further investigation of this conventional technique has led to the development of a new method called the original mixing method (FIGS. 2a and 2a).
b). 2a and 2b, the air 8 and the fuel gas 9 are mixed in advance before combustion, and the mixed air is sent to the chamber 10 to make the mixed air uniform, and the average mixed gas is ejected from the combustion plate 11. . The mixed gas ejected to the combustion chamber side of the combustion plate is ignited and burned. The combustion method as shown in FIGS. 2a and 2b is called a planar combustion method, and since the fuel gas and air are mixed before combustion, they are called the original mixing method.

When the combustion is carried out by such a method, the combustion progresses evenly and the NOx value generated can be reduced. In particular, the influence of the air mixing ratio is large, and when the air mixing ratio is large, the NOx value is greatly reduced. However, when the same investigation as that of the burner shown in FIGS. Certainly, if the air mixing ratio is increased, a low NOx value can be obtained, but from the viewpoint of thermal efficiency, it is advantageous to reduce the air mixing ratio because exhaust gas heat loss can be reduced. Also, from the viewpoint of CO ₂ reduction, which has been a hot topic recently, reduction of exhaust gas heat loss is effective. That is, in order to reduce CO ₂ , it is advantageous to reduce the air mixing ratio.

[0007]

As described above, the low NO
Although the development of the x-burner has progressed, it is necessary to further develop a combustion method that can obtain a low NOx value in a situation where the air mixing ratio is small in order to reduce CO _{2 as} well. The air mixing ratio is 1.1 to 1
In the high efficiency range of 1.2, it is necessary to further reduce NOx.

[0008]

The gas burner with a low NOx value according to the present invention has been achieved by successfully combining the advantages of the original mixing method and the prior mixing method. The burner based on the premixing method uses gas as fuel, mixes a part of the fuel gas (primary gas) and air, and a dividing plate that divides the mixed fuel gas and air into a plurality of jets. And a mechanism for ejecting the rest of the fuel gas (secondary gas) to the combustion side of the dividing plate. The burner based on the original mixing method uses a gas as a fuel and mixes a part of the fuel gas (primary gas) with air, a chamber for homogenizing the mixed fuel gas and air, and a fuel plate. And a mechanism for ejecting the rest of the fuel gas (secondary gas) to the combustion side of the combustion plate.

In any of the systems, the common means is that not all fuel gas is mixed with air, but a part (primary gas) of the fuel gas is mixed with air in advance and burned, and the rest of the fuel gas is mixed. The (secondary gas) is directly injected into the combustion part.

In the original mixing method, it is estimated from the prior art 2 of FIG. 5 that a low NOx value can be obtained when the air mixing ratio is large. Therefore, when mixing the fuel gas and the air, the method of mixing a part of the fuel gas in advance in the flame, and increasing the mixing ratio of the air, and mixing the remaining fuel gas in the flame directly By taking it, it became possible to solve it.

[0011]

EXAMPLES Example 1 An explanatory view of a gas burner according to the present invention is shown in FIGS. 3a and 3b. 3a and 3b show an example of the present invention based on a low NOx gas burner using a conventional premixing method. The part different from the burner of the conventional premixing method is the gas header, and in this embodiment, the primary gas header 1
5 and the secondary gas header 16 are provided in two stages. Figure 3 below
A description will be given based on a and b.

The fuel gas advances in the direction of the arrow, and when it passes through the primary gas header 15, a part of it (primary gas) is ejected from the primary gas nozzle 13 to the mixing section 17. On the other hand, the combustion air is rectified through the wind box 7 and enters the combustion cylinder 3. The air and the fuel gas ejected from the primary gas nozzle 13 form a mixed gas having a large air ratio in the mixing section 17, and are divided into plural pieces by the dividing plate 20 and ejected. The dividing plate 20 is described as being divided into eight in FIG. 2B, but the number of dividing, the dividing area, and the like may be the same as those of the flame holding plate used in the conventional low NOx burner. Simultaneously with the jet, a pilot burner (not shown in the figure) ignites a flame with a large air ratio. The remaining fuel gas (secondary gas) is the secondary gas header 16
Then, the secondary gas nozzle 14 ejects the flame into the flame. The amount of the fuel gas ejected from the secondary gas nozzle is preferably adjusted to 3 to 50% by volume of the whole fuel gas as the balance (secondary gas).

In this embodiment, an example in which the secondary gas nozzle is ejected from the central portion of the gas burner has been shown. However, when the dividing plate 20 is large, the secondary gas nozzles may be dispersed and ejected in several parts. it can. The secondary gas can be jetted in a direction parallel to the flame, but if a small hole is opened near the tip of the jet port and the secondary gas is jetted at a right angle or at an angle as shown in FIG. The mixing with is more efficient.

The fuel gas (primary gas) discharged from the primary gas nozzle is mixed with air, but 5% of the total fuel gas is discharged.
When it is 0 to 97%, good results are obtained in this embodiment. As for the ratio of fuel gas (primary gas) to air, a lower NOx value can be expected as the ratio of air increases, as shown in Prior Art 2 of FIG. But if the absolute amount of fuel gas is small,
Thermal efficiency decreases. The secondary gas ejected from the secondary gas nozzle maintains the thermal efficiency.

A combustion test was carried out using the gas burner of Example 1 shown in FIGS. 3a and 3b. As the fuel gas, generally used natural gas was used. The NOx value generated by gradually changing the mixing ratio of air to the fuel gas was measured by a commercially available exhaust gas analyzer (chemiluminescence method). The primary gas ejected from the primary nozzle of the fuel gas was 70% of the total fuel gas. The obtained NOx value is shown in Example 1 of FIG. From this result, compared to the values of the premixing method (conventional technology 1) and the original mixing method (conventional technology 2), the NOx value may be low in the region where the air mixing ratio of 1.1 to 1.2 is large. Recognize.

(Embodiment 2) In Embodiment 1, the embodiment of the gas burner in which the distribution ratio of the primary gas and the secondary gas is fixed is shown, but in FIG. 4, the distribution ratio of the primary gas and the secondary gas is made variable. An example is shown. In FIG. 4, the fuel gas (secondary gas) supplied to the secondary gas header is supplied through the branch pipe 19 without passing through the primary gas header, and the metering valve 2 is provided in the middle of the branch pipe 19.
This is an example in which 1 is attached. The amount control valve 21 is adjusted to make the amount of secondary gas variable, and the distribution ratio with the primary gas can be adjusted. The amount of secondary gas is preferably 3 to 50% of the total fuel gas. The branch pipe 19 and the secondary gas header 16 can be interlocked and moved back and forth. There is an advantage that the ejection position of the secondary gas can be adjusted with respect to the flame.

(Embodiment 3) The present invention can be applied to a gas burner of the original mixing method. FIG. 5 shows an example thereof. The gas burner has an air inlet 8 and a fuel gas inlet (fuel gas 9), and joins at a gas mixing port 12. A branch pipe 19 is provided in the middle of the fuel gas pipe, and this pipe passes through the chamber 10 and the combustion plate 11 and projects to the combustion side of the combustion plate, and reaches the residual gas ejection port 18. The mixed gas mixed at the gas mixing port 12 is supplied to the chamber 10
A uniform flow is generated, and a flame is formed at the same time as being ejected from the combustion plate 11. Metering valve 2 attached to the branch pipe 19
At 1, the distribution ratio of the primary gas and the secondary gas is adjusted. Pilot burners etc. are omitted.

In this embodiment, the residual gas (secondary gas) is collectively ejected into the flame for ease of explanation. However, if the area of the combustion plate is large, it is possible to eject it in several places. Taken. When jetting at multiple locations, it is also effective to attach a metering valve individually and adjust the jet rate by the flow of fuel gas. When various flame conditions are to be changed, a means for attaching an adjusting device that can be installed back and forth to the branch pipe 19 can be provided so that the position of the residual gas ejection port is adjusted appropriately. The residual gas jet 18 can be jetted directly in parallel with the flame, but as shown by the arrow in the residual gas jet 18 portion of FIG. 5a, the tip of the jet is blocked,
It is efficient to make a small hole at the tip and eject the gas with a direction or angle orthogonal to the flame.

The distribution of the mixed gas to be fed in and the balance of the fuel gas can also be adjusted according to the situation of use. The distribution of the primary gas supplied from the gas mixing port 12 and the secondary gas supplied from the residual gas ejection port 18 can be expected to be low NOx because the mixing ratio of air increases as the amount of secondary gas increases. However, if the amount of the secondary gas is increased too much, the mixture ratio of the air-fuel mixture ejected from the combustion plate 11 becomes too high, and combustion cannot be continued. Therefore, the amount of the secondary gas falls within the range of 3 to 50% of the entire fuel gas. preferable.

[0020]

By using the gas burner according to the present invention, a low NOx value can be secured and highly efficient combustion can be achieved.
Reduction of CO ₂ makes it environmentally friendly.

[Brief description of drawings]

FIG. 1 (a) is a side view of an example of a gas burner using a prior art premixing method. (B) A front view of an example of a gas burner using a prior art premixing method.

2 (a) is a side view of an example of a gas burner using a prior art source mixing method. FIG. (B) It is a top view of the example of the gas burner using the original mixing method of a prior art.

FIG. 3 (a) is a side view of an example of a gas burner according to the present invention. (B) It is a top view of the example of the gas burner which becomes this invention.

FIG. 4 is a side view of another embodiment of the present invention.

FIG. 5 (a) is a side view of another example of the gas burner according to the present invention. (B) It is a top view of another example of the gas burner which becomes this invention.

FIG. 6 shows N in the case where the air ratio of the embodiment and the prior art is changed.
It is a graph of Ox values.

[Explanation of symbols]

1 gas nozzle 2 flame retaining plate 3 combustion cylinder 4 gas header 5 pilot burner 6 electrode rod 7 wind boxes 8 Air inlet 9 Fuel gas 10 Mixer chamber 11 burning plate 12 gas mixing port 13 Primary gas nozzle 14 Secondary gas nozzle 15 Primary gas header 16 Secondary gas header 17 mixing section 18 Residual gas outlet 19 Branch pipe 20 division plates 21 Metering valve

Continued front page    (72) Inventor Hiroyuki Mizuno             Osaka, Hirakata-shi             Leh Cold Heat Co., Ltd. F-term (reference) 3K017 AA06 AB07 AC03 AD03 CA06                       CB02 CB08 CE05                 3K019 AA06 BA04 BB04 BD01                 3K065 TA01 TA14 TB01 TD05 TF01                       TG04 TH01 TH03

Claims (8)

[Claims] 1. A burner using gas as a fuel, which mixes a part of the fuel gas (primary gas) and air, and a dividing plate which divides the mixed fuel gas and air into a plurality and jets them out. A gas burner having a mechanism for ejecting the rest of the fuel gas (secondary gas) to the combustion side of the dividing plate. 2. A burner using gas as a fuel, comprising a part for mixing a part of the fuel gas (primary gas) and air, a chamber for making the mixed fuel gas and air uniform, and a combustion plate. A flat combustion type gas burner having a mechanism for ejecting the rest of the fuel gas (secondary gas) to the combustion side of the combustion plate. 3. The gas burner according to claim 1, wherein the distribution ratio of a part of the fuel gas (primary gas) and the balance of the fuel gas (secondary gas) is fixed. 4. The distribution ratio of part of the fuel gas (primary gas) and the balance of the fuel gas (secondary gas) is variable by a branch pipe and a metering valve. Gas burner described. 5. The distribution ratio of a part of the fuel gas (primary gas) and the balance of the fuel gas (secondary gas) is a volume ratio of the primary gas:
The gas burner according to any one of claims 1, 2 and 4, wherein the secondary gas is in the range of 50:50 to 97: 3. 6. The gas burner according to claim 1, wherein a single outlet is provided for the remaining portion (secondary gas) of the fuel gas. 7. The gas burner according to any one of claims 1 to 5, wherein a plurality of jets of the remaining portion (secondary gas) of the fuel gas are provided. 8. The gas burner according to claim 1, wherein the injection position of the remaining portion (secondary gas) of the fuel gas is variable.